Abstract 165: Amp-activated Protein Kinase (ampk) α1 in Macrophages Promotes Collateral Remodeling and Arteriogenesis in Mice

Abstract

Efficient arteriogenesis is vital for recovery after cardiovascular events (such as chronic coronary occlusion, myocardial infarction). Identifying the biological factors that affect arteriogenesis will help design new treatments for patients with chronic arterial stenosis and occlusions. Circulating monocytes and macrophages recruited within the surrounding tissue of collateral vessels following arterial occlusion have been reported to be essential to arteriogenesis in collateral arteries/arterioles because they promote the proliferation of vascular smooth muscle cells (VSMCs) and endothelial cells through secreted cytokines. Although a growing number of putative arteriogenic factors have been identified, the exact mechanisms that regulate collateral remodeling have remained largely unknown. Here we report that AMPK, an energy and redox sensor, is required for monocyte-mediated collateral remodeling. Collateral arteriogenesis was monitored in WT, global AMPKα1 knockout (KO), or macrophage-specific AMPKα1 KO mice with or without hind limb ligation. Compared to WT mice with ligation, global AMPKα1 KO mice displayed significant reduction in blood flow recovery and impaired remodeling of collateral arterioles. Similar impairments were observed in macrophage-specific AMPK α1 KO mice following hind limb ligation. Mechanistically, we found that AMPKα1 promotes the production of growth factors, such as transforming growth factor beta, by directly phosphorylating the inhibitor of nuclear factor kappa B (NF-κB) kinase alpha, resulting in an NF-κB-dependent production of growth factors. Collectively, our findings suggest a novel role for macrophage AMPKα1 in arteriogenesis and collateral remodeling and indicate that AMPKα1 activation might be a therapeutic target for treating occlusive vascular disorders.